Steel cord for radial tire

Abstract

A steel cord comprising at least 10 metal filaments and having an elongation of 0.015-0.045% under a load of 0.5 kgf, an elongation of 0.025-0.060% under a load 1 kgf, and an elongation of 0.060-0.114% under a load of 4 kgf, assuming that the elongation under a load of 0.05 kgf is 0%, has a soft twist construction and is suitable to be used in the carcass of a radial tire for truck and bus.

What is claimed is: 
     
       1. A radial tire twisted-steel cord of circular cross-section comprising at least ten metal filaments which are multi-layered and in a soft twist configuration, comprising an outer layer of said filaments being arranged with a clearance of between 0.009 and 0.015 mm between adjacent filaments in said outer layer and between the outer layer and the adjacent inner layer, the cord having a load-elongation characteristic which lies between:   a curve I defined by the relationship y=815.47x 2  +18.09x+0.05 and   a curve II defined by the relationship y=368.57x 2  -6.59x+0.05,   where x represents the elongation (%) of a cord and y represents the load (kgf) applied to the cord, and lying within the range of 0.05-4.00 kgf, and said steel cord having an elongation of 0.015-0.045% under a load of 0.5 kgf, an elongation of 0.025-0.060% under a load of 1 kgf, and an elongation of 0.060-0.114% under a load of 4 kgf, when the elongation under a load of 0.05 kgf is 0%.